APR 21, 2019 12:39 PM PDT

Increase in the Prevalence of Fabellae Over 150 Years

WRITTEN BY: Dena Aruta

 

Sesamoid bones are embedded in a tendon or muscle, and they are located in areas that have "high mechanical stimuli," such as physical activity, friction, or exercise. Their function is to protect the tendon from injury by decreasing friction. The patella is the largest sesamoid. The fabella is located behind the lateral femoral condyle and is embedded in the tendon of the lateral head of the gastrocnemius muscle. The fabellofibular ligament stabilizes the fabella, and it can also function as an additional origin of a muscle fascicle of the popliteal muscle.  While the fabella is commonly seen in non-human mammals, its prevalence in humans varies greatly from 3-87% and is considered a normal anatomical variant. The highest prevalence rates are found in Australians and Asians, and the lowest rates are found in South Americans and Europeans. 

 

Figure 1. Large, medium, and small (L to R) ossified fabellae. Credit: Berthaume, Di Federico, and Bull

 

Because of this wide variation in the prevalence of the fabella, Michael Berthaume, PhD and colleagues performed a comprehensive literature review to "calculate the prevalence of the fabella in a Korean population and investigate possible temporal shifts in the prevalence rate." Samples were taken from CT scans that had previously been collected. They included 212 knees from 106 Korean individuals, who were between the ages of 21 and 60 and heights between 146 to 178 cm (4' 8" and 5' 8"). Since CT scans don't distinguish between fabellae that are cartilaginous or bony, they didn't make the distinction in the study. "Our literature search yielded 58 studies on fabella prevalence rates from 1875–2018 which met our inclusion criteria," states Michael Berthaume. 

After analysis of the data, Berthaume and colleagues "found no increase in prevalence rates of 10 other sesamoid bones in the human body, indicating that the increase in fabella prevalence rate is unique. Fabella presence/absence is due to a combination of genetic and environmental factors: as the prevalence rates of other sesamoid bones have not changed in the last 100 years, we postulate the increase in fabella prevalence rate is due to an environmental factor." The prevalence in Koreans for knees (52.83%) and individuals (44.34%) has increased in the last 80 years. 

Even though there has been a significant increase in fabella prevalence, there has not been an increase in other sesamoid bones in the body. "We are unsure why this has occurred," states Berthaume; however, they hypothesize that the increase in height and weight from improved nutrition and increases in tibial length and muscle mass may cause enough mechanical stimuli for the fabella to form and ossify. 

 

 

About the Author
  • After earning my Bachelor of Science degree in biology/chemistry from Virginia Polytechnic Institute and State University (aka Va. Tech), I went on to complete clinical rotations in laboratory medicine at Roanoke Memorial Hospital. I spent the next 21 years working in healthcare as a clinical microbiologist. In 2015, I combined my fascination with medicine and passion for writing into a freelance career, and I haven't looked back. Even though my expertise is in microbiology and infectious diseases, I'm adept at writing about any medical topic. Being a freelance writer allows me to pursue a career where I can work at home with my two feline assistants, Luke and Grace. I'm a firm supporter of animal rights and volunteer for a local rescue during my free time. 
You May Also Like
MAR 19, 2020
Drug Discovery & Development
MAR 19, 2020
Could a 1949 Malaria Drug Treat COVID-19?
In the race to halt the current coronavirus pandemic, scientists, health experts and even Elon Musk are considering chloroquine, a drug that has been used ...
MAR 25, 2020
Cardiology
MAR 25, 2020
Staying Fit While Avoiding COVID-19
For those used to working out at a gym, the current circumstances requiring us all to remain isolated as much as possible might be throwing off their routi...
MAR 28, 2020
Drug Discovery & Development
MAR 28, 2020
Could the Blood of Coronavirus Survivors Save Lives?
As the search for a treatment for coronavirus continues, a perhaps obscure-sounding candidate has begun to make headlines: blood containing antibodies from...
MAR 29, 2020
Genetics & Genomics
MAR 29, 2020
Biomarkers That Predict Crohn's Disease Are Identified
A series of studies published in Gastroenterology has outlined new approaches in predicting IBD....
APR 01, 2020
Immunology
APR 01, 2020
New Airway-Hugging Immune Cells Discovered in the Lung
  Scientists have discovered a previously unknown subset of immune cells residing in the lung that specifically combat viral infections. The respirato...
APR 04, 2020
Clinical & Molecular DX
APR 04, 2020
AI Finds New Predictive Markers of Covid-19 Severity
Researchers and healthcare organizations are putting their heads together to consider how technology could ease the ever-worsening COVID-19 global crisis....
Loading Comments...